             ttRow)))
 
 (defn- timetable-row-empty?
-  "Returns true if there is no lesson for a given day and row in `Timetable`.
+  "Returns true if there is no lesson for a given day and row in `TIMETABLE`.
    Returns false otherwise."
   ([ttRow] (empty? ttRow))
 

  [day rowNum]
  (nth (timetable-get-day day) rowNum))

; First argument is a day in `Timetable - the return value of
; `timetable-get-day` function
(defmethod timetable-get-day-row false
  [ttDay rowNum]


(defn- timetable-row-not-empty?
  "Returns true if there at least one lesson for a given day and row in
   `TIMETABLE`. Returns false otherwise."
  ([ttRow] (not (timetable-row-empty? ttRow)))

  ([day rowNum] (not (timetable-row-empty? day rowNum))))
